Yet another excellent application for nuclear bombs. These things really don't get enough love. Here's a fairly cheap device (only tens of millions of $s) that could allow us to launch thousands of tons to space at just dollars per pound. This is the Verne Gun. Such a simple, beautiful idea. Drill a borehole a few miles into the ground, set off a 150-kiloton nuclear bomb at the bottom, and use the shockwave to propel a capsule (called a Wang Bullet for some reason) into space. The cost of constructing the Verne Gun would be in the tens of millions.
I'm not sure how easy it is to appreciate the sheer power of this system. It can launch 3000 tons to orbit in one shot. The ISS weighs about 400 tons. All sorts of crazy stuff we could do with this. Just three launches would equal roughly 10,000 tons. This would be easily enough for a real, sci-fi type space station. I did some math based on the mass of the Bigelow Aerospace modules (100 tons for BA2100), and if we chained them together in a circle, we would get something absolutely massive. Based on back-of-the-envelope calculations we could have a torus roughly 500 meters in circumference and a 20 meter cross section. Easily big enough to spin for artificial gravity. That's a conservative estimate. Easily big enough to have an orbital town with hundreds of residents and its own little economy. A space venture of that magnitude could more than pay for itself. The industrial possibilities are endless: zero-gravity manufacturing (perhaps in a module in the center), tourism (read: space hotels), and more. SpiderFab technologies could likely reduce the cost of assembly by a lot.
And note that this is just three launches. Imagine ten or a hundred or a thousand.
This only works for bulk cargo, but that alone could revolutionize everything, almost as much as having a working Orion drive. Could we see it built? I'm not so sure. I don't agree with Yuli Ban--or Matthew--very often, but they're on the money here--Americans these days have a cowardly, lily-livered attitude towards cutting-edge science, quaking in fear at the slightest mention of "nuclear" or "genetic engineering". We need to up our game big league or certain authoritarian regimes that shall go unnamed will go roaring past us. Our current attitude won't do. We need the spirit of American innovationism back again. We need to learn to shout 'Never tell me the odds!' and not get bogged down in regulations and petty boondoggles. We need to rip the space treaties and 75 percent of the business regulations to shreds and release myriad companies into the Final Frontier. Maybe Trump will lead us in that direction. We shall see...